We don’t know what’s at the bottom of the Great Lakes. Climate change demands we find out

CHICAGO – We know less about the bottom of the Great Lakes than we do about the surface of Mars, according to Jennifer Boehme.

The oceanographer is executive director of the Great Lakes Observing System, an Ann Arbor, Michigan-based nonprofit leading a concerted effort to fully map the world’s largest freshwater body from coast to coast, surface to floor.

Only 15% of the lakebed has been documented to modern standards, which could have major consequences for coastal communities as climate change makes storms and floods more frequent and severe. Without an understanding of how the depth and contours of the lakebed are shifting, scientists cannot accurately predict how extreme weather will affect natural habitats and built infrastructure.

“There are questions that need to be answered about coastal safety for the Great Lakes, but we can’t answer them because basic information is missing,” Boheme said. “For me, it’s very much a safety issue.”

The Great Lakes, which nearly 40 million people in the United States and Canada depend on for drinking water, have already taken a beating from climate change. Water levels dropped this fall to the lowest in years, affecting shoreline ecosystems, access to docks and shipping routes.

Most of the imaging taken of the Great Lakes is decades old and low resolution. It does not show the pipelines, cables, shipwrecks and boulders that new technologies make visible.

Updated, high-resolution imaging has been taken piecemeal over the years, primarily to inform shipping routes and targeted research. When Boehme and her team began their concerted effort in 2019, 12% of the lakes had been mapped to modern standards.

They called the initiative Lakebed 2030, intending to complete the project in 2030. But in the last five years, the Great Lakes Observing system has only mapped another 3% of the lakebed.

Systematically creating a holistic picture of the lake’s bathymetry — the underwater equivalent of topography — is a massive undertaking. The five Great Lakes have a combined surface area of 94,250 square miles, roughly the size of the United Kingdom. And they vary greatly, with depths ranging from 210 feet in Lake Erie to over 1,300 feet in parts of Lake Superior. If all that water was spread across the contiguous United States, the nation would be evenly submerged in nearly 10 feet of water.

The primary roadblock is money. The Great Lakes Observing System estimates mapping all five lakes will cost $200 million. The money would be spent on a combination of advanced sound and light detection technologies over approximately a decade.

Halfway to 2030, they’re rethinking the initiative name.

“What we’ve been calling Lakebed 2030 could morph into a more organized and concerted effort. We’re calling it ‘Building the Great Map,’” said Boheme.

Nevertheless, the time pressure remains as weather events become more extreme. The amount of rain falling in the heaviest 1% of storms in the Great Lakes region has increased by 35% over 66 years.

Earlier this year, Michigan U.S. Rep. Lisa McClain introduced the Great Lakes Mapping Act, a bipartisan bill directing the National Oceanic and Atmospheric Association to conduct high-quality mapping of the Great Lakes lakebeds.

“The Great Lakes generate ($)6 trillion to America’s GDP and support over 51 million jobs, yet we have barely scratched the surface of understanding the depths of the lakes,” said McClain, a Republican. “Investing in comprehensive exploration will offer an enhanced look at the potential these bodies of water offer to bolster our economy and inform efforts to protect one of America’s greatest natural resources.”

The bill sits in the House Natural Resources Committee, and McClain plans to reintroduce it next Congress should it not make it to the floor this year.

It’s unlikely to pass in President-elect Donald Trump’s Washington, however. Project 2025, a political framework affiliated with several of his recent Cabinet picks, aspires to abolish the federal agency in charge of weather forecasting and climate monitoring.

This isn’t deterring Boheme, who said the team will continue seeking private funding to complete the ambitious project. At the end of the day, the oceanographer is confident the undertaking will pay dividends beyond the intangible benefits of protecting wildlife and public safety.

Knowledge about lakebed movements could help industries, from shipping to recreation, better plan their activities. Mapping would also likely create permanent jobs; data would constantly need to be updated as climate change-induced weather events dramatically shift the lakebed.

Ultimately, the Great Lakes Observing System plans to make the lakebed map accessible to everyone and easy to use.